This invention is concerned with hollow structures such as multi-panel hollow doors having molded skins, and is more particularly concerned with improved paperboard cores for such doors.
Hollow doors with molded skins have become increasingly popular in recent years. Because the skins are flexible, it is necessary to provide some type of core, void filler, or separator between the skins to ensure the desired rigidity of the door. In doors having flat or flush skins without panels, the core may take the form of a simple multi-cellular structure (honeycomb) constituted of corrugated paperboard. However, a problem arises when a skin has panels defined by peripheral indentations, because the separation of the skins is not uniform.
One approach to solving this problem is to use a multi-cellular paperboard core in which the height of the cell walls varies to accommodate the indentations. However, this arrangement increases the complexity of core manufacture and door assembly. Another approach is to use a plurality of separate paperboard "build-ups" or pads between the skins, but this arrangement increases material requirements.